The present invention relates to a dual band slot antenna, and in particular to a dual band slot antenna with a single feed line.
There is a growing need for dual band antennas for use in wireless communication devices to adapt the devices to dual band operation. Referring to FIG. 1, a conventional dual band slot antenna comprises an antenna body 101 made from a metal foil, a first and second closed-circle slots 11, 12 defined in the antenna body, and a first and second coaxial cables 30, 50 electrically connecting with the antenna body 101, wherein the first coaxial cable 30 has an inner core wire and an outer shield respectively soldered to two sides of the first slot 11 to act as a feeder of the first slot 11, and the second coaxial cable 50 has an inner core wire and an outer shield respectively soldered to two sides of the second slot 12 to act as a feeder of the second slot 12. With such a structure, the antenna can operate in two different frequency bands using by the two different slots 11, 12 with the two feeders 30, 50.
However, since this arrangement requires two coaxial cables, such dual band slot antenna will occupy more installation space. Furthermore, the second coaxial cable adds manufacturing cost.
Hence, an improved antenna is desired to overcome the above-mentioned shortcomings of existing antennas.
A primary object, therefore, of the present invention is to provide an improved dual band slot antenna with a single feed line to save installation space and manufacturing cost.
A slot antenna in accordance with the present invention comprises an antenna body with elongated first and second slots defined therein and a coaxial feeder cable having a conductive inner core wire and a conductive outer shield. The inner core wire is electrically connected to the antenna body at an outer side of the first slot and the outer shield is electrically connected to the antenna body at an outer side of the second slot. The coaxial cable acts as a common feed line of the first and second slots.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings.